Conventionally, a single reel tape cartridge incorporates a locking mechanism for preventing unnecessary rotations of a tape reel while not in use which would otherwise cause an unwanted tape slack.
For example, JP 2001-256756 A discloses a locking mechanism, called flange locking mechanism, having a gear formed on the outer peripheral surface of the reel flange and an associated gear formed on the locking lever pivotally mounted on the housing of the cartridge and capable of engaging and disengaging the gear of the reel to lock and unlock the reel.
Also, JP 2003-187548 A discloses another locking mechanism, called hub locking mechanism, having a gear formed on the central bottom surface of the hub and an associated gear formed on the opposing surface of the reel biasing member and capable of engaging and disengaging the gear of the hub to lock and unlock the reel.
Further, JP H05-225746 A discloses a tape cartridge with a flange-less tape winding member in which a hub lock mechanism is provided between an inner peripheral surface of the central opening defined in the bottom wall of the tape housing through which a drive mechanism is accessed and the hub of the tape winding member. A ring-like stopper is provided in the lower portion of the inner surface of the hub. Also, gears are provided on the lower peripheral surface of the stopper and the inner peripheral surface of the opening, respectively, and the stopper is biased by the compression spring to engage its gears with the associated gears on the opening. This prevents the relative rotation between the stopper and the hub but allows a relative sliding movement in the vertical direction. The upper end of the spring biasing the stopper into the locking position is received by the downwardly opened upper wall of the hub.
Each of above described conventional reel locking mechanisms needs independent locking lever or locking member, and/or the unlocking member, which results in an increase of the number of components required for the locking mechanism and the overall manufacturing cost of the tape cartridge.